They plan to strike Jan. 3.

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More than 1,000 nurses at one of Manhattan's top private hospitals are planning a one-day strike in January after negotiations over a new contract broke down, mainly due to a disagreement over health care premiums.

The nurses filed notice with St. Luke's-Roosevelt Hospital Center in Manhattan that they will strike on Jan. 3, the union that represents them said. The New York State Nurses' Association said the strike notice was given during a marathon 18-hour bargaining session that ended at 4 a.m.

Unionized nurses have threatened to strike at two other major hospitals, raising the prospect of about 6,000 nurses walking off the job in the next couple of weeks.

Nurses at Montefiore Medical Center in the Bronx and Mount Sinai in Manhattan, where negotiations were under way Thursday, also have authorized the union to strike.

Continuum Health Partners Inc., which operates St. Luke's Hospital, did not immediately respond to requests for comment.

Jesse Derris, a spokesman for Montefiore hospital, said the hospital hopes to resolve the disagreement "quickly and amicably." Mount Sinai Hospital did not respond to a request for comment.

Bernie Mulligan, a spokesman for the union, said three main issues are tying up negotiations at all three hospitals: health care benefits, fair wages, and safe staffing levels. He said at the top of that list is a push by the hospitals to get unionized nurses to pay premium contributions for health care and for prescriptions.

Ralph Spencer, a registered nurse in the Psychiatric Department at St. Luke's and a member of the local bargaining unit, said the health care premiums would be a financial burden.

"We believe that if we are going to be providers of health care in our community, then our health should be taken care of," he said.

Nurses at all three hospitals have been working without a contract since December 2010, and the union is currently negotiating three-year contracts. At St. Luke's, the association said it has had 25 bargaining sessions in an attempt to reach a new agreement.

"Our members at the hospital and our bargaining team are continuing to send the message to the hospital that we want to resolve this dispute," Mulligan said. "We don't want to go on strike."